Production of methyl borate and boric acid prom crude sodium nitrate



R. P. CALVERT AND 0mm. THOMAS. PRODUCTION OF METHYL BORATE AND eomc' Acm FROM CRUDE somum NITRATE.

APPLICATION FILED NOV. 5, I917.

Patented July 1,1919.

BY J4} A TTORNE Y I UNITED. ,sTATEs A omen.

ROBERT P. CALVERT AND OTHO L. THOMA PORATIION OF DELAWARE.

S, OF WILMINGTON, DELAWARE, ASSIGNORS TO E. I. DU PONTiDE NlEMOURS AND COMPANY, OF WILMINGTON. DELAWARE. A COR- PRODUCTION' OF METHYL BORATE AND BORIC ACID FROM CRUDE SODIUM NITRLATE.

Application filed November 5, 1917. Serial No. 200,438.

To all whom it may concern:

Be it known that we, llonmrr P. (.xnvnnr and O'rno L.'.luow.\s. of Wilmington, in the county of New Castle. and in the State of Delaware, have invented a certain new and useful Improvement in Production of Methyl Borate and Boric Acid From Crude Sodium Nitrate; and do hereby declare that the following is a full, clear. and exact description thereof.

Our invention relates particularly to a process for treating crude sodium nitrate, as for example Chili saltpcter, and especially the product obtained in the Chili salt peter industry, which contains a high percentage of potassium nitrate, to obtain an alkyl'borate, such as methyl borate and boric acid therefrom.

The object of our invention is to provide a process by means of which methyl borate and boric acid may be produced from crude sodium nitrate, and particularly the product of the Chili saltpeter industry, which c0ntains a high percentage of, potassium nitrate,-that is to say, from 20% to 50% of potassium 'nitratc -and which contains, furthermore, from 3% to 7% of boric acid, as well as other impurities, such as sodium ehlorid, calcium sulfate, sand, potassium perchlorate and water.

Theobject of our invention is, furthermore, to remove the boric acid, so as to ren der the residual materials suitable for uses to which the product could not otherwise be applied, as for example, the production of refined saltpeter and refined sodium nitrate.

Further objects of our invention will appear from the detailed descriptiouthereof contained hereinafter.

While our invention is capable of being carried out in many different ways, we shall describe herein only certain ways of carrying out the same, and, while it is capable of being used inconnection with many different typcs of apparatus, we shall describe onlyonetype. of apparatus for use in connection therewith and in the accompanying drawings, in which The figure is a diagrammatic representation of an apparatus which may be used in connection with our invention.

In the drawings we have shown a jacketed still 1, having a steam inlet 1" and a steam outlet-1 for heating the still. The still is furthcrprovided with a valved filling, pipe 1 for methyl alcohol and a gage glass 1, a vapor outlet pipe 2, which has an inlet pipe 2'' for air or steam, said pipe 1' being an ranged to deliver the vapor lhcrct'rom into a rotary drum 3, having hollow trunnions 4 and 4, carried in suitable supports 5 and 5. The drum 3 is adapted to be rotated by means of peripheral gears (3. meshing with a gear 7 on a shaft 8, )assing through the supports 5, and adapted to be driven from any suitable source of power. The drum 3 has a heating jacket 9, adapted to be supplied with steam through the hollow trunnion 4, which connects with a steam supply pipe 10, while the condensed steam is carried ott' through a pipe 10, A manhole 10" in the drum 3 permits the entry and exit of the solid materials for the same. The vapors from the drum '3 pass out through a pipe 11, which is connected to a condenser 12, having an outlet pipe 13, leading toa frm-tionating still 14. The still 14 has a water inlet pipe 13, connected to the pipe. 13, a draw-off pipe 13", and a vapor outlet pipe 15, leading to a prinmry condenser 15 having a trap return pipe 15 leading to the vapor outlet, pipe 15, and thence to acondenser 16, from which the condensed materials are drawn oil through an outlet pipe 17.

For GXtLll'llJlQ, our invention may be earricd out as follows: A quantity of an alcohol, for example methyl alcohol is intro duced into the still 1 and heat applied thcrcto in any suitable manner, while a quantity of saltpeter high in potassium nitrate, and having the composition above referred to. is introduced through the manhole It)" into the rotary drum 3. For example, 40 parts of methyl alcohol'amd 100' parts of the saltpeter may be. used for this purpose. This amount of methyl alcohol is more than sullicient to combine with the horic acid present. The"teniperaturo ot' the maintained at from -l()" to i20 CL, bllt usually at about 70 (h, for a icriod of several minutes, while the drum is being rotated. Thereafter the volatile compounds in the drum 3 are distilled out. of the said drum,

Patented July 1, 1919.

drum 3 is" so that they pass off through pipe 11 to the latter or mixes with it in part, thus producing a vapor which carries oil the boric acid. The vapor comprises methyl alcohol, containing boric acid and methyl borate. The distillate collects in the still l-l. If desired the removal of the volatile materials from the drum 3 may be assisted by the injection of a" current of air or steam by means of the pipe 2. Into the distillate in the still 14, 8 parts of water are then introduced through the pipe 13. As a result, the methyl borate is hydrolyzed to produce methyl alcohol and boric acid. Heat being applied to the still 14, the methyl alcohol and small amounts of unchanged methyl borate pass into the condenser 16 and are drawn ofi' byrthe pipe 17. The boric acid remains dissolved in the water in the still 14, and may be drawn oil from the same by the pipe 13 and crystallized out therefrom by cooling the solution. The mixed nitrates which have thus been purified by. the re.-

' moval of the boric acid therefrom may be separated in any suitable manner to produce pure potassium nitrate and pure sodium nitrate in any Suitable manner; for example, in accordance with the processes set forth in the applications of Robert P. Calvert, on process of separating nitrates of potassium and sodium, Serial Number 183,821, filed August 1, 1917, and Andrew S. Yount, on method of separating nitrates of potassium and sodium, Serial Number 183,871, filed August 1, 1917.

Instead, however, the liquid may be treated by adding thereto a quantity of potassium chlorid, while the filtrate is still hot, sufficient to convert the materials in solution to saltpeter and sodium chlorid; as for example, 70 parts of potassium chlorid. The sodium chlorid and saltpeter maybe then se arated bycrystallization.

ile we have described our invention above in detail, We wish it to be understood that man changes may be made therein without teparting from the spirit of our invention.

We claim:

1. The process which comprises separatingboric acid from mixtures containing the same by adding a lower monohydric alcohol thereto and volatilizing the compound formed by the alcohol and the boric acid.

2. The process which comprises separating boric acid from mixtures of nitrates contaming the same by adding a lower monohydric alcohol thereto and volatilizing the compound formed by the alcohol and the y, boric acid.

8. The process which comprises separating boric acid from mixtures containing the same by adding methyl alcohol thereto and Volatilizing the compound formed by the alcohol and the boric acid.

4. The process which comprises separating boric acid from mixtures of nitrates containing the same by adding methyl alcohol thereto and volatilizing the compound formed by the alcohol and the boric acid.

The process which comprises separating boric acid from mixtures containing the same by adding an alcohol thereto. volatilizing the compound formed by the alcohol and the boric acid, condensing the vapors thus produced, and hydrolyzing the distillate.

6. The process which comprises scparating boric acidfrom mixtures of nitrates containing the same by adding a lower monohydric alcohol thereto, volatilizing the compound formed by the. alcohol and the boric acid, condensing the vapors thus produced, and hydrolyzing the distillate.

7. The process which comprises separating boric acid from mixtures containing the same by adding methyl alcohol thereto. volatilizing the compound formed by the alcohol and the boric acid, condensing the vapors thus produced, and hydrolyzing the distillate.

8. The process which comprises separating boric acid from mixtures of nitrates c0n taining the same by adding methyl alcohol thereto, volatilizing the compound formed by the alcohol and the boric acid, condensing the vapors thus produced, and hydrolyzng the distillate.

9. The process which comprises separating boric acid from mixtures containing the same by addin a lower monohydric alcohol thereto, volatilizing the compound formed by the alcohol and the boric acid, condensing the vapors thus produced, hydrolyzing the distillate, and distilling off the alcohol.

10. The process which comprises separating boric acid from mixtures of nitrates containing the same by adding a lower monohydric alcohol thereto, volatilizin the compound formed by the alcohol anal the boric acid, condensing the vapors thus produced, hydrolyzing the distillate, and distilling ofl 1 the alcohol.

11. The process which comprises separating boric acid from mixtures containing the same by adding methyl alcohol thereto, volatilizing the compound formed by the alcohol and the boric acid, condensing the vapors thus reduced, hydrolyzing the distillate, and distilling oil the alcohol.

12. The process which con'ipriscs separating boric acid from mixtures of nitrates contaming the same by adding methyl alcohol thereto, volatilizing the compound formed by the alcohol and the boric acid. condensing the vapors thus produced. hydrolyzin the distillate, and distilling oil the alcoho 13. The proccss which comprises separating boric acid from miXtures containing the same by adding a lower monohydric alcohol thereto, volatilizing the compound formed by the alcohol and the boric acid, condensing the vapors. thus produced, hydrolyzing the alcohol, and crystallizing out the boric acid distillate, distilling off the alcohol, and crysfrom the residue.

tallizing out the boric acid from the residue. In testimony that we claim the foregoing 14. The process which comprises separat- We have hereunto set our hands. 5 mg borlc acid irom mixtures of nitrates con- ROBERT P. CALVERT.

taming the same by adding a lower monohydric alcohol thereto, volatilizing the compound formedby the alcohol and the boric Witnesses:

acid, condensing the vapors thus produced, G. D. I'IOPKINS, .10 hydrolyzing the distillate, distilling oil the S.' L. ABRAMB,

OTHO L. THOMAS, 

